chromium/third_party/blink/web_tests/fast/multicol/nested-outer-fixed-height.html

<!DOCTYPE html>
<style>
    .mc { -webkit-columns:2; -webkit-column-gap:0; }
</style>
<p>Test that we establish two column rows for the contents of an inner multicol container that
    crosses a column boundary in the outer multicol container.</p>
<p>The word "PASS" should be seen below, with large letter spacing, and no red.</p>
<div class="mc" style="column-fill:auto; width:4em; height:2em; line-height:2em; background:red;">
    <div class="mc" style="background:white;">
        P<br>
        A<br>
        S<br>
        S<br>
    </div>
</div>